docs: def convenience_split_params(self, params, return_all_types=False):
          """
          Splits parameter vector into shape, intercept, and index parameters.
  
          Parameters
          ----------
          params : 1D ndarray.
              The array of parameters being estimated or used in calculations.
          return_all_types : bool, optional.
              Determines whether or not a tuple of 4 elements will be returned
              (with one element for the nest, shape, intercept, and index
              parameters for this model). If False, a tuple of 3 elements will
              be returned with one element for the shape, intercept, and index
              parameters.
  
          Returns
          -------
          tuple. Will have 4 or 3 elements based on `return_all_types`.
          """
          return self.split_params(params,
                                   return_all_types=return_all_types)